Revert "Add precompiled headers to GN build for large targets."

cc/BUILD.gn

Index: cc/BUILD.gn
diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index c4cdb2d1dc8e2e0a0a70a34ccae6ae2bef261803..67daed5fab145bdd7d902cfb2e4c296225468c4d 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn
@@ -509,8 +509,6 @@ component("cc") {
     ]
   }
 
-  configs += [ "//build/config:precompiled_headers" ]
-
   public_deps = [
     "//cc/base",
     "//skia",
@@ -664,7 +662,6 @@ source_set("test_support") {
     "test/test_web_graphics_context_3d.h",
   ]
 
-  configs += [ "//build/config:precompiled_headers" ]
   include_dirs = [
     ".",
     "test",
@@ -848,7 +845,6 @@ test("cc_unittests") {
     "test/run_all_unittests.cc",
   ]
 
-  configs += [ "//build/config:precompiled_headers" ]
   data = [
     "test/data/",
   ]